Saved Bookmarks
| 1. |
In all metallic conductors, electric conduction is due to drifting of free electrons. But the resistivity of different metals are different.1. Write the expression for resistivity of a conductor in terms of its dimensions.2. Name the factors on which resistivity of a metal depends.3. Arrive at an expression for electrical resistivity of a metal in terms of relaxation time.4. Using the above expression explain the variation of resistivity with temperature. |
|
Answer» 1. ρ = \(\frac{RA}{l}\) 2. Temperature and Nature of metal 3. We know current density J = nvde But Vd = \(\frac{eE}{m}\tau\) ∴ \(\bar J=n.\frac{e\overrightarrow E}{m}\tau e\) \(\bar J=\frac{ne^2}{m}\tau \overrightarrow E\) \(\bar{J}=\sigma\overrightarrow E\) where \(\sigma = \frac{ne^2}{m}\tau\) But ρ = \(\frac{1}{\sigma}=\frac{m}{ne^2\tau}\) 4. When temperature increases, the amplitude of oscillation of atom increases. This will decrease . the relaxation time and hence resistivity increases. |
|